A study was conducted on the flotation with oleic acid of sedimentary phosphates from Sierra Espuna, in the province of Murcia (Spain), also comprising an analysis of the kinetic considerations governing the operation. Two different flotation cells were used for this purpose, i.e. a Hallimond tube and a subaeration cell (Denver D-12). The results achieved with the Hallimond tube show that the rate of mineral flotation is medium to slow, while results with the Denver D-12 cell reveal a faster rate of flotation. It also became clear that the separation of the phosphate and calcareous fractions of the mineral (CaCO3) is more intense at the very beginning of the operation. The flotation rate constants for mineral sizes between 160 and 325 ASTM mesh were determined, and a linear relationship between flotation rate constant and mineral sizes was shown to exist.